The role of γδ T cells in the immunopathogenesis of inflammatory diseases: From basic biology to therapeutic targeting.

Gamma-delta T cells are lymphocytes with an innate-like phenotype that can distribute to different tissues to reside and participate in homeostatic functions such as pathogen defence, tissue modelling and response to stress. These cells originate during foetal development and migrate to the tissues in a TCR-chain-dependent manner. Their unique manner to respond to danger signals facilitates the initiation of cytokine-mediated diseases such as spondyloarthritis and psoriasis, which are immune-mediated diseases with a very strong link with mucosal disturbances, either in the skin or the gut. In spondyloarthritis, gamma delta T cells are one of the main sources of IL-17, and therefore, the main drivers of inflammation and probably new bone formation. Remarkably, this population can be the bridge between gut and joint inflammation.